The invention relates to a device for sealing a ring gear which is driven by a pinion which dips into an oil bath.
Large rotating machine parts, such as rotary kilns, tube mills, rotary dryers and the like, are predominantly driven by means of ring gears which are mounted on their outer periphery and pinions which engage therewith and which are in turn part of a drive assembly. A proportion of the lubrication oil is transferred to the teeth of the ring gear by the driving pinion running in an oil bath. While a proportion of the transferred oil drips off of the half of the ring gear located at the lowest point at that time and can flow back into the oil bath, the remaining quantity of oil is carried with the teeth of the ring gear into the region above the axis of rotation of the ring gear. There is then a danger that the oil may flow off along the body of the ring gear as far as the casing of the rotary kiln and this can result not only in greater oil losses (through vaporisation), but as a consequence of the relatively high casing temperature (even up to approximately 400.degree. C. in case of breakdown) there can be a considerable danger of fire.
For the reasons set out above efforts have been made to provide appropriate sealing arrangements in the region of the ring gear so as to prevent flowing off of the entrained oil in the direction of the body of the ring gear or the casing of the rotary kiln.
In a construction which is known in the art and is intended especially for sealing a ring gear mounted on a rotary kiln casing, rings of circular cylinder shape which are at least partially enclosed by stationary sheet metal strips are provided in the region of the end faces of the ring gear. During operation the circular cylindrical ring slides along the sheet metal strip and together with the latter forms the actual seal. It should be borne in mind here, however, that in the case of rotating drums concentricity errors (height and tumbling motion out of true), axial movements of the ring gear and alterations caused by thermal stresses can occur, which can have very serious effects in the case of rotary kilns. Even if such errors and movements can to some extent be accommodated resiliently, it is not possible to prevent uncontrolled lubrication conditions occurring as a result of the given relative rotational movements of the essential sealing elements, and this can lead to undesirably severe wear.